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Commit fc8a168a authored by Nikolay Borisov's avatar Nikolay Borisov Committed by David Sterba
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btrfs: Check for missing device before bio submission in btrfs_map_bio 



Before btrfs_map_bio submits all stripe bios it does a number of checks
to ensure the device for every stripe is present. However, it doesn't do
a DEV_STATE_MISSING check, instead this is relegated to the lower level
btrfs_schedule_bio (in the async submission case, sync submission
doesn't check DEV_STATE_MISSING at all). Additionally
btrfs_schedule_bios does the duplicate device->bdev check which has
already been performed in btrfs_map_bio.

This patch moves the DEV_STATE_MISSING check in btrfs_map_bio and
removes the duplicate device->bdev check. Doing so ensures that no bio
cloning/submission happens for both async/sync requests in the face of
missing device. This makes the async io submission path slightly shorter
in terms of instruction count. No functional changes.

Reviewed-by: default avatarJosef Bacik <josef@toxicpanda.com>
Reviewed-by: default avatarAnand Jain <anand.jain@oracle.com>
Signed-off-by: default avatarNikolay Borisov <nborisov@suse.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent ab457246

fs/btrfs/volumes.c

+2 −7
Original line number Diff line number Diff line
@@ -6109,12 +6109,6 @@ static noinline void btrfs_schedule_bio(struct btrfs_device *device, 
	int should_queue = 1;

	struct btrfs_pending_bios *pending_bios;



	if (test_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state) ||

	    !device->bdev) {

		bio_io_error(bio);

		return;

	}



	/* don't bother with additional async steps for reads, right now */

	if (bio_op(bio) == REQ_OP_READ) {

		btrfsic_submit_bio(bio);
@@ -6243,7 +6237,8 @@ blk_status_t btrfs_map_bio(struct btrfs_fs_info *fs_info, struct bio *bio, 


	for (dev_nr = 0; dev_nr < total_devs; dev_nr++) {

		dev = bbio->stripes[dev_nr].dev;

		if (!dev || !dev->bdev ||

		if (!dev || !dev->bdev || test_bit(BTRFS_DEV_STATE_MISSING,

						   &dev->dev_state) ||

		    (bio_op(first_bio) == REQ_OP_WRITE &&

		    !test_bit(BTRFS_DEV_STATE_WRITEABLE, &dev->dev_state))) {

			bbio_error(bbio, first_bio, logical);